This invention relates generally to golf balls, and more specifically, to multilayer golf balls. In particular, this invention relates to a golf ball having at least one core or cover layer comprising high-Mooney-viscosity regrind.
There are a variety of different types of golf ball constructions, the majority of which, however, fall into two general categories: solid and wound golf balls. Solid golf balls include one-piece, two-piece, and multi-layer golf balls. One-piece golf balls are inexpensive and easy to construct, but have poor playing characteristics and are, therefore, usually limited for use as range balls. Two-piece balls are generally constructed with a polybutadiene solid core and a cover and are typically the most popular with recreational golfers because they are very durable and provide good distance. These balls are also relatively inexpensive and easy to manufacture, but are regarded by top players as having limited playing characteristics. Multi-layer golf balls are comprised of a solid core and a cover, either of which may be formed of one or more layers. These balls are regarded as having an extended range of playing characteristics, but are more expensive and difficult to manufacture than are one- and two-piece golf balls.
Wound golf balls, which typically include a fluid-filled center surrounded by tensioned elastomeric material and a cover, generally provide higher spin and soft xe2x80x9cfeelxe2x80x9d characteristics but are more difficult and expensive to manufacture than are one-piece, two-piece, and multi-layer golf balls. Manufacturers are, therefore, constantly striving to produce a solid ball that incorporates the beneficial characteristics of a wound construction.
A variety of golf balls have been designed by manufacturers to provide a wide range of playing characteristics, such as compression, velocity, xe2x80x9cfeel,xe2x80x9d and spin. These characteristics can be adjusted and optimized for a variety of playing abilities. For example, manufacturers can adjust these properties by altering the materials (i.e., polymer compositions) and/or the physical construction of each or all of the various golf ball components (i.e., centers, cores, intermediate layers, and covers). Polymers commonly employed by manufacturers for the construction of golf balls include polybutadiene (cores), ionomers, such as SURLYN(copyright), commercially available from DuPont (covers and intermediate layers), and polyurethanes (covers and intermediate layers). Finding the right combination of core and layer materials and construction to produce a golf ball suited for a predetermined set of performance criteria, in particular, increased resilience and, therefore, velocity, without a loss in xe2x80x9cfeelxe2x80x9d is a task that is challenging.
It is desirable, therefore, to construct a ball having a soft, thin, urethane cover layer a harder, thin, ionomer inner cover layer, coupled with a polybutadiene center and an outer core layer, at least one of which contains high-Mooney-viscosity regrind, balata, or both. The present invention describes a variety of compositions and constructions employing high-Mooney-viscosity and balata, particularly in center and core layers, for increasing resiliency and improving processing of the material.
The present invention is directed to a golf ball comprising a core and a cover layer, wherein the core has an outer diameter of no greater than about 1.62 inches; the cover layer comprises an inner cover layer and an outer cover layer having a material hardness of less than about 60 Shore D; and at least one of the core or the cover includes high-Mooney-viscosity rubber, high-Mooney-viscosity rubber regrind, or a mixture thereof.
In one embodiment, the core comprises a center and at least one outer core layer. The high-Mooney-viscosity rubber or regrind should have a Mooney viscosity of between about 40 and about 80 and, preferably, between about 45 and about 60.
The high-Mooney-viscosity rubber regrind is present in an amount of no greater than about 20 weight percent of the total polymer composition and, more preferably, between about 5 weight percent and about 20 weight percent and, most preferably, in an amount of between about 8 weight percent and about 16 weight percent.
The core outer diameter is from 1.4 inches to about 1.62 inches and, in another embodiment, the outer core layer has an outer diameter from about 1.4 inches to about 1.62 inches. At least one of the cover layers comprises a polyurethane composition comprising the reaction product of at least one polyisocyanate, a polyol, and at least one curing agent and, additionally, at least one of the center or the outer core layer comprise high-Mooney-viscosity rubber regrind. In a preferred embodiment, the outer core layer comprises high-Mooney-viscosity rubber regrind.
The inner cover layer has a material hardness less than about 72 Shore D and, preferably, less than about 68 Shore D. At least one of the inner or outer cover layers includes ionic copolymers of ethylene and an unsaturated monocarboxylic acid; vinyl resins; polyolefins; polyurethanes; polyureas; polyamides; thermoplastic and thermoset resins; metallocenes; acrylic resins; thermoplastic polyesters; nonionic copolymers and terpolymers; or a mixture thereof.
At least one of the core or cover layers are cast, reaction injection molded, liquid injection molded, injection molded, or a combination thereof. In an alternative embodiment, the core has a moment of inertia of less than about 83 and a center deflection of greater than about 4.5 mm under a load of 100 Kg. The outer cover layer also can have a material hardness of less than about 58.
The present invention is also directed to a golf ball comprising a core and a cover layer, wherein the core comprises a solid center and an outer core layer and has an outer diameter of less than about 1.62 inches; the cover layer comprises an inner cover layer and an outer cover layer, the outer cover having a material hardness of no greater than about 58 Shore D; and wherein at least one of the core or outer core layer comprises a mold assisting blend including high-Mooney-viscosity rubber, high-Mooney-viscosity rubber regrind, and balata.
The present invention is further directed to a golf ball comprising a core and a cover layer, wherein the core comprises a solid center and an outer core layer and has an outer diameter of between about 1.4 and about 1.62 inches; the cover layer comprises an inner cover layer and an outer cover layer, the outer cover having a material hardness of no greater than about 58 Shore D, and the inner cover layer has a material hardness of less than about 72; and wherein the outer core layer comprises a mold assisting blend comprising high-Mooney-viscosity rubber, high-Mooney-viscosity rubber regrind, and balata.